Wild nuts such as acorns, pine nuts and pistachios are highly cariogenic, or those "producing and promoting the development of tooth decay"

Ancient human farmers suffered from cavities galore, as attested by fossil evidence, and scientists usually have connected tooth decay to the shift from hunting and gathering to farming. As people grew more plants around 10,000 years ago, the thinking went, they ate more fermentable carbohydrates and created a favorable oral environment for Streptococcus mutans,a type of bacterium that delights in causing tooth decay. Now, however, new evidence has emerged to refute the idea of hunter-gatherers with pearly white teeth. Thanks to a diet high in nuts, some hunter gatherers' rotten breath and cavity-filled teeth rivaled those of their agriculturally inclined descendants.

The researchers reached this conclusion after studying the decay-ridden teeth of 15,000-year-old adult skeletons from Morocco. Just over 50 percent of the teeth they examined in 52 skeletons showed signs of rot, Wired UK reports. That figure's similar to the incidence of tooth decay in agricultural societies that emerged a few thousand years down the line. The "exceptionally high" number of cavities, the authors write, is also "comparable to modern industrialized populations with a diet high in refined sugars and processed cereals." The ancient Moroccans in question "would have suffered from frequent tooth ache and bad breath," co-author Isabelle DeGroote told Wired.

The nutty cause of all this decay, the team determined, was a diet rich in gathered acorns and pine nuts. Using mass spectroscopy, they also found some evidence of juniper berries, wild oats and pistachios. Those wild nuts, the authors point out, are highly likely to produce tooth decay, and the invention of toothbrushes was still a while away.